Usability in the real world

I washed my filthy car yesterday at one of the do-it-yourself car washes. I don't know why, I always feel ripped off at these. Having control over the cleanliness of my car is a bad thing too, since I ALWAYS miss a spot, then I only have myself to blame. This was the interface given.

• A dial with the different steps of the carwash process and two "Stop"s
• A slot to put in quarters, a place for rejected quarters
• A light saying the station is operation
• Another light saying you're on your last coin
• A blurb telling you to put in six quarters slowly

First things that are wrong with this:

1. What order do I do these steps in? There was a giant poster on the wall to my left, but the dial should be order, clockwise. There appeared to be no order to the dial. The top half is "high pressure" things, the bottom is "other". There may be a mechanical reason for the order, but why do I, the user, care about how the back end of this dial works?
2. How long will six quarters give me? It would increase the cost of this interface if it gave a digital "time remaining" display. But the "Last coin alert" is easy to miss. And if you run out of time, you have to start over with the base six quarters.
3. *NO WHERE* does it say that you can buy more time with more quarters. If someone didn't know how these places work, they might assume they could actually wash their car for $1.50. When in fact, $1.50 is just enough to cover your car with suds, but not enough to wash it off.

The first time I went to this station, I started with tire cleaner and began spraying the tires. When I got to the third tire, the sprayer sputtered and started spraying green tire cleaner... I now know better and stand there with "tire cleaner" selected for 20-25 seconds until it starts working.

There may be a lot of marketing involved in how this particular station works. Things to slow the customer down slightly enough that most wouldn't notice, but enough to eek out a few more bucks a day. So, things to learn from this to take into the web.

• Put controls in a logical order and put the instructions *ON* the control. Turning my head 90 degrees to see what the next recommended step isn't much of a problem, but why should I have to. If the dial was in a useful order, you wouldn't have to even look at the dial. But as is, every step I have to careful choose what's next.
• Have your controls operate as they logically should. Otherwise you'll leave visitors feeling stupid. "Tire cleaner" took a long time to start working. You could relate this to locking your application while key information is being refreshed, so that users don't keep using the old information.